Gonbes CGA->VGA upscaler knowledge base (GBS-8200/GBS-8220)

[newsdee]

Recently spent a few weekends trying to sort out issues with a GBS-8200.  I learned quite a few things from disjointed forum posts across sites;
so thought I'd compile a consolidated list of info/resources. This is not exhaustive, so feel free to contribute/suggest changes and I'll update items as we go.

Who makes these cards?
These are made by Gonbes.
The model numbers are GBS-8200 / GBS-8220.  They mostly look the same except the 8220 has 2 VGA D-SUB 15 connectors in output.
http://en.gonbes.com/product_detail.asp?menuid=94&id=22

What is it?
It's a pcb card for video upscaling, that can convert a 15Khz RGBS input (e.g. from a JAMMA board) or a composite (YPbPr) signal into a more conventional 31 Khz VGA output, compatible with most modern monitors and LCD/LED TVs (which no longer recognize 15Khz).
Commonly used to convert old consoles/computers to a VGA signal, upgranding old cabs into newer monitors, and superguns of course.

How well does it work?
Your mileage may vary. Many people seem to be happy with it but many others have a number if issues.
Outputs 60Hz so may be worse if your input is 50Hz. (I've only tried 60 Hz)

What are the issues?
The upscaling applies a bit of smoothing, which you can reduce using a "sharpness" setting.
When in operation you may see some noise with some pixels flickering. This is barely noticeable (it's pixels of the output resolution so they're small) and some TVs may correct it (haven't tried).
You may have sync issues if your grounding or power source is not good enough.

Does it slow down the video?
Probably but not as far as I can tell. The movement feels like 60Hz.
I can notice some interlacing in some shadows (ie. for strong black flickering on white) but it's massively better than the FPS being put out by a Multi PCB for example (30 fps).
(update: using a scanline filter improves the interlacing by hiding some of it. still noticeable but plenty playable)

What's your take on it?
My own experience is ok. There's minor noise in places (flickering dots or some colors bleeding into another - not big issue but you can tell it's not a PC).
The noise is are more or less noticeable at different resolutions.
I initially had sync issues - it would work fine for about an hour then the image would start to jump. That was due to a power supply that was not strong enough when it heated up.

What's the difference between the GBS-8200 and the GBS-8220?
As far as I can tell the only difference between the two seem to be an extra VGA output, probably a clone of the display.
I only tried the 8200, so if anybody has more info, please share.

Do I need a sync cleaner?
Not for Superguns / JAMMA inputs. It would be needed if you connect a console or computer from it though.

How to tell if it's genuine?
Don't know. Apparently there are bootlegs of the card floating around that don't work as well.
Mine looks identical to the one on Gonbes website, with the chinese title with a "III" on it.

Is it better than a XRGB?
The GBS is worse because: has noise of some pixels flickering, is very sensitive to input voltage, and the two voltage inputs seems to work differently (had issues with the "DC in" with one power supply, but the "molex" input worked well). The XRGB handles more resolutions and is better at supporting 50hz signals.
Other than that an XRGB upscaler costs 10 times more than the GBS, so I would hope it works better

If I get a scanline filter do I need a different power supply?
No - I saw on a video somebody using DC in on the GBS for the power supply, then chaining the scanline filter through the molex connector.
The GBS actually has two power connectors, and it turns out that you can use one to connect another device.
The SLG-3000 is 5V as well, so the setup works very well.

What PSU do I need?
5V 2A at least. Any less (lower voltage or not enough amperage)  will give you a red or blue screen with blocks (even without an input signal).
Apparently the GBS8200 can accept 12V, but reportedly this seems to heat it which leads to different issues after running for some time.
Gonbes website states 5V +/- 0.5, so stick to 5V.
Personally, I use the same power supply as my JAMMA harness. Otherwise, I get sync issues (which could be due to grounding perhaps, I have not tried another setup).
If you have a "bouncing" image (bad sync), it could be due to the power supply not being strong enough.

[newsdee]

References/Links

Manual/Setup Guides

• User Manual from Gonbes
• Setup Guide
• Review/Setup Guide from supadave

Review / Discussions

• My issues with the converter
• discussion (and pics) at the Neo Geo forums
• Review from blaine
• another discussion at the Neo Geo forums
• Discussion on customizing the firmware to get more options and fix some issues

Videos

[newsdee]

Updated a few entries after using an SLG-3000 (great buy - once you try scanlines it's hard to go back).

[CraftyMech]

Thanks for posting all this info. I have one of these converters and it works pretty well @ 640x480, but the glitches are a little annoying. What I notice most is jittering when bitmaps get close to one another (such as a ghost in Ms. Pac-man moving along a wall). I've cycled through all the settings, but have not had any luck improving the quality. Using scanlines helps a bit, but the defects are still obvious when playing low-res games like Donkey Kong or Pac Man. Interesting thing is I have observed the same behavior when connecting my 60-in-1 board, or my Namco 25th Ms Pacman/Galaga board. I might end up looking at another converter, but there are not that many to choose from, and the GBS-8200 was about 1/2 the price of the competition.

[CraftyMech]

A bit off topic, but an interesting fun fact about the 60-in-1 board, if you set the dip switch for CGA output, the HSync line on the VGA adapter will be 15khz, and the RGB signal lines will be running on the CGA pixel clock as well.

[CraftyMech]

I have a Legend of Kage board and have used a fingerboard to adapt the board to Jamma. The GBS-8220 refuses to display a picture, just "no signal". Scope output on the sync line shows a 15k hsync, and there is lots of activity on the RGB lines. I've read the GBS was designed for Jamma RGBs signals, but shouldn't the CGA output from a non-jamma CGA 15k board be the same standard? The hync line looks fine, and not noisy at all. Any thoughts?

Update: The GBS-8200 turned out to be a little fickle, the video from the Legend of Kage board is just fine. I split the CGA composite sync into separate H/V signals, and fed the video into the GSB board using the 8pin cable they provide. Image displayed just fine, so there was something about the composite sync on my Kage board that the GBS didn't like.

[newsdee]

I think the glitches are due to the "quality" of the chip that does the upscaling.

For your CGA composite signal, I'd imagine it should work if you connect it to the VGA input?
I did have some funny issues with an X-in-1 board though - both settings gives me an image, but one screws up the colors.

[schmosef]

Has anyone found any info on what's changed with the newer revisions of these boards?

I recently bought an arcade cab with an GBS-8200 v2.0 board in it that connects to an LCD monitor (replaced a failed CRT).

I can see online that the GBS-8200 v4.0 is currently available. I'm wondering what the difference might be.

Also, other than the second VGA output, are there any performance benefits of the GBS-8220 over the GBS-8200?

[CraftyMech]

I have the v4 board, dated 2010/5/12 on the pcb.

Users on the KLOV forum have reported that the older v2 boards had some compatibility problems with pre-Jamma games, and also with non-standard vertical refresh rates (under 60hz).

That said, my v4 board refuses to sync to Raiden 2 (refresh rate ~57hz), and can't hold a steady picture with Mr. Do! So I'm not sure how much of an improvement the later version is in reality, maybe I'm unlucky to have two boards the Gonbes doesn't like.

I believe the only difference between the 8220 & 8200 is the second VGA output.

[opt2not]

Didn't see this thread before. I got redirected here from another thread...
Nice topic, and thanks for the info!

Here's a necro-bump question:  Anyone know a good cheap source for these?  I've been searching and so far, the cheapest I've found is on fleEbay.  I need at least 2 of these...perhaps 3 for some small projects.

[CraftyMech]

The cheapest I have seen them is on eBay as well, usually around $28.

[opt2not]

Yeah, figured so...

Ok doke. Ebay is it.

Crafty, I'll be in touch about your SLG's soon.

[ChadTower]

One more datapoint:

I have the red VGA-2P clone of that board.  The main differences are the red PCB and an added J5 input for .156.

I'm trying to get this thing to work with a Pole Position II and it just isn't going to happen.  I can get it to the point where the pic is clear but bouncing around.  I can get that on the little input and the .156.  It just won't sync cleanly to Pole Position II.   

To be sure I pulled the older version out of my Berzerk and that known working one acts just like the red one so I know it's this particular title.

[UR]

Hi,

I have one of this (GBS-8200). I wanted to use it with my old device which has CGA/EGA output. This device it is not an arcade game, but I thought it will work. But there nothing happens. It says "no signal". Then I tried to measure some signal. I figured that H-Sync frequency is 20.7 kHz and V-sync is 56 Hz. What can I do know ? As far as I know this board doesn't support that kind of input freqencies.
Thanks for help !

[CraftyMech]

What is your device?

CGA = Arcade Standard Res / 15k RGB video

EGA = Arcade Medium Res / 25k RGB video

[UR]

Like I wrote, H-Sync frequency is 20.7 kHz, so I don't know what type device is: CGA or EGA. I suppose is EGA.

[CraftyMech]

Like I wrote, H-Sync frequency is 20.7 kHz, so I don't know what type device is: CGA or EGA. I suppose is EGA.

I actually meant what kind of device is it? Computer, console, etc..

[UR]

It's equipment in car workshop.

[CraftyMech]

It's equipment in car workshop.

My hunch is you are not going to be able to get the Gonbes converter to sync to that equipment's video signal. The Gonbes can be pretty picky about video timing, and both your horizontal and vertical refresh rates are outside of what the Gonbes expects (H: 15k, 25k) (V: 60hz).

Is there a dip switch or firmware setting where you can change the output resolution? You mentioned your device has CGA/EGA output, so perhaps there is a low resolution mode (CGA) that outputs 15k.

[SailorSat]

There are various "frame grabber" that allow "non standard" scan rates.
Another option would be an old "multisync" Monitor (Microvitec/Amiga M1438) or something like that.

[4bviper]

Hooked up my GBS-8220 to my Street Fighter 2: Hyper Fighting cabinet without much problems.  Out from the VGA port of the GBS-8220, I have a VGA to HDMI scaler which in turn is connected to my Elgato HD60.  Hoping to do some game captures from my cabinet.

However when I power everything up, there's two issues:
1)  The image outputted to the VGA port is upside-down.  This is driving me nuts.  I can't find a way to rotate the screen right-side up.
2)  The image on the original cabinet monitor gets pretty dim even if I boost the brightness and constrast.  When I unplug the RGB harness from the GBS-8220, the colors return back to normal.

Any suggestions to help me fix these problems would be greatly appreciated.  Thanks in advance!

[4bviper]

Solved my screen upside-down problem by flipping the yoke wires.

Now gotta figure own the screen dimming issue...

[fireslayer26]

Need help wiring a GBS 8200 to my Ivan Off Road driving arcade. On the Main board wiring diagram its showing connection P1 as:

Blank
Gray - Horizontal Sync
White - Vertical Sync
Black - Ground
Red - Red
Blank
Green - Green
Blank
Blue - Blue
Blank

I have tried every way possible to get this wired right and nothing has worked. A few times it was showing a brief flash of the game screen, then going to a black "no signal". But I could never get it to stay. I am using the 8-pin connector on the GBS8200. Blue to blue, red to red, green to green, Black to black, grey to grey, white to yellow.  I have also tried leaving the yellow disconnected. Nothing works. Any thoughts??

Thanks

[Howard_Casto]

I bought a gbs 8200 v4 the other day and I'm wondering if I got a dud. 

I also bought a snes ntsc scart cable , which I broke apart as I'll eventually be using vga connectors.  I haven't gotten out of the testing stage though.  The board refuses to find the signal.  The cable uses pin 3 on the snes (I checked) which should be a clean, composite sync.  I have the csync hooked up to the gray "sync" pin on the included harness.  Once in a blue moon the video may appear and sync for a split second but usually it's "no signal".  I also have the needed caps hooked up btw.  I read on one site that the composite sync signal the snes puts out is too high, so I added a 680ohm resistor to the sync line as instructed, but no luck. 

I also tried hooking it up to a genesis, which again is supposed to have a clean sync.  It did seem to sync more often, but there wasn't any picture to speak of... it was mostly a green field.  Again though, most of the time "no signal".

I tried various power supplies.  A portable hdd power supply (12v 2a) a puny universal power supply at 5 and 12v and another universal @ 1A at 4.5 and 12v.  I know that 2amps is supposed to be required, but this is what I have lying around to test with.  I guess I could pull a power supply later.

Am I doing something wrong or is there something I can do to test the board?  I don't have any arcade pcbs on hand as I bought this for consoles. 

[Howard_Casto]

So nobody can help either one of us then?

I hooked mine up to a proper pc power supply and still had the same issues, so I think I've ruled out power. 

[fireslayer26]

I had an old 19" arcade monitor lying around, so I hooked that up to the Offroad game. Still had a scrambled signal. Noticed on the back of the monitor it had a switch. 15.3khz or 17khz. On 15.3 the signal was scramble, but when I switched it to 17khz to video worked. I read on the specs of the GBS8200 it can work up to 16.5khz.  Is this why it is not working on the LCD screen. Also, the old monitor would not work when the horizontal and vertical signal wires were hooked to the + connections, but when I put them on the - connections it would work. 

I can't figure this thing out. The GBS8200 is such a pain in the --I'm attempting to get by the auto-censor and should be beaten after I re-read the rules--!!!!!

[mistakrayz]

Wanted to check on the progress on the Ivan off-road.  ?
I am in the same situation with this game.  Solid green screen flashing with a No Signal message. I have my wires setup up the same.  Gray to Gray White to Yellow.

Thanks for any input... LCD monitor

[arcadeswede]

Is it possible to connect let say a NES with only composite video to this converter?
I read somewhere that the green component RCA jack input can also serve as a composite video input, at least on HDTV and such.

Can someone confirm this?